Dendrobium "frosty dawn" help-blotchy yellow leaves

[Kdykens]

I just bought a "Frosty Dawn" Dendrobium about two weeks ago and somehow I am already killing it. It arrived via mail looking awesome-even blooming a bit. It seemed dry so I watered it, let it drain thoroughly on a paper towel, and put it on the kitchen counter. Three days later the flowers started to wilt. Then leaves at the base of two smaller stalks began to drop off. Now it's the big main stalk as well. Probably six leaves have turned a blotchy yellow with black/brown spots and died. I'm assuming it isn't a deciduous thing as they are not uniformly yellow. It is sunny in my kitchen but I have lots of shade tolerant plants in here with no problem. I would say the temp range is 67-75 degrees. Help me!!!! How did I manage to kill a healthy plant in two weeks?!?! Pic of leaves attached. Rest of plant looks healthy w full stalks and buds forming.